[0.16.1390] Raider dances between two flanked spots

[carbon]

This probably isn't technically a bug, more a weird edge case of the combat AI unable to cope with the situation, where hopefully some minor improvements could be made.

The raider 'Skye' is located at an exterior corner of a building. Either side of the corner is flanked by one of my colonists. Instead of pulling back to a piece of cover that isn't flanked (there are several around), Skye will continue to dance between the two sides of the corner seemingly forever.

Save file of the situation attached. I have disallowed firing of the two colonists doing the pinning, so you should get several seconds of good dancing to enjoy.

[attachment deleted by admin due to age]